[Analysis of the Characteristics of Nitrogen and Phosphorus Emissions from Agricultural Non-point Sources on Hanfeng Lake Basin].

Abstract

To understand the status of agricultural non-point source pollution and to find out the primary pollution sources and the key control areas in the Hanfeng Lake Basin, the discharges of total nitrogen (TN) and total phosphorus (TP) from farming, livestock and poultry breeding, and rural living in thirty-two counties in 2015 were estimated using the pollutant discharge coefficient method. The spatial distribution characteristics of the quality and intensity of the TN and TP emissions from these sources were investigated using the GIS spatial analysis method. Pollution evaluation and source analysis were also carried out using the equivalent pollution load method. The results show that the total loads of TN and TP in the Hanfeng Lake Basin are 2721.42 t and 492.04 t, respectively. The discharge of pollutants is the largest in the Nanhe Basin and the smallest in the area around Hanfeng Lake. The total pollutant loads from the agricultural non-point sources varied greatly, with fertilizer application and livestock and poultry breeding being the main sources. The contribution from fertilizer application is 76.92%, which represents the primary source of TN and TP pollution in the Hanfeng Lake Basin. Among the townships, the equivalent pollution loads of Dunhao, Tieqiao, and Baiqiao are higher than 350 m3·a-1; thus, these are the key control towns. According to the results of the equivalent pollution method and cluster analysis, the 32 counties were divided into four types of pollution areas. These areas are planting-livestock breeding dominant area, fertilizer-livestock breeding dominant area, fertilizer dominant area, and heavily polluted planting dominant area.